JPH0824661A - Catalyst and method for isomerization of xylenes - Google Patents

Abstract

PURPOSE:To isomerize xylene contating ethylbenzene with a catalyst, to accomplish the dealkylation of ethylbenzene and the balanced isomerization of ortho- xylene and meta-xylene into para-xylene, to control hydrogenation-decomposition of a benzene ring, and to improve the recovery rate of xylene. CONSTITUTION:The catalyst for the isomerization of xylene characterized by containing zeolite in which less than 50% of the cation sites are replaced with hydrogen ion and which has a main void size of a ten-membered ring of oxygen and the method for the isomerization of xylenes are prouded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention In the present invention, xylenes containing ethylbenzene are contacted with a specific catalyst in the gas phase in the presence of hydrogen to isomerize the xylenes and to convert ethylbenzene to other aromatic hydrocarbons. It is related to the conversion to.

[0002]

2. Description of the Prior Art Of the xylene mixtures, the currently industrially important ones are p-xylene and o-xylene. p-
As a raw material for synthetic fiber polyester, xylene has been significantly increased in demand so far. It is expected that the trend will not change in the future. O-xylene is used as a raw material for a plasticizer phthalate ester of polyvinyl chloride. However, at present, the demand for o-xylene is smaller than that for p-xylene. On the other hand, m-xylene has almost no industrial use. From this, it is industrially very important to convert o-xylene and m-xylene into p-xylene.

Since the boiling points of the xylene mixture are close to each other, especially the boiling points of p-xylene and m-xylene are very close, it is economically disadvantageous to separate p-xylene by a distillation method.

Therefore, industrial separation of p-xylene has been carried out by cryogenic separation utilizing the difference in melting points. In the case of the cryogenic separation method, the recovery rate of p-xylene per pass is limited due to the eutectic point, which is at most (60%) / pass. As a result, the p-xylene concentration in the raffinate fluid after recovering the p-xylene is fairly high.

On the other hand, Japanese Patent Publication No. 49-17246, 49-2
8181, 50-10547, 50-11343, 51
An adsorption separation method has been developed as a new separation technology as disclosed in Japanese Patent Publication No. 46093/460. In this adsorption separation method, 100% of p-xylene can be recovered per pass. That is, p- in the raffinate fluid after adsorption separation
The xylene concentration is extremely low and theoretically becomes zero. So far, o-xylene has generally been separated by precision distillation. The remaining raffinate fluid from which p-xylene and o-xylene are separated in this way is sent to the isomerization step, and m-xylene and / or o-xylene is isomerized to a p-xylene concentration close to the thermodynamic equilibrium composition. And then mixed with fresh feed and sent to the separation process and the cycle is repeated. In such a combination process, when the remaining raffinate fluid obtained by separating p-xylene by cryogenic separation is fed to the isomerization step, the concentration of p-xylene in the raffinate fluid is relatively high as described above. , P-xylene adsorption separation method, in the case of a raffinate fluid, p-
The xylene concentration is extremely low. Therefore, the reaction in the isomerization step requires greater severity in the latter case.

Generally, xylene raw materials used industrially are reformed oil type xylene obtained by reforming naphtha and then aromatic extraction and fractional distillation, or cracked gasoline by-produced by thermal decomposition of naphtha. It is a cracked oil-based xylene obtained by aromatic extraction and fractional distillation. The characteristic feature of cracked oil type xylene is that the concentration of ethylbenzene is twice or more higher than that of the reformed oil type.
The typical composition is shown in Table 1.

[0007]

[Table 1]

As described above, generally, a considerable amount of ethylbenzene is present in the xylene mixture, but if ethylbenzene is not removed by any means, ethylbenzene accumulates as the separation step and the isomerization step are recycled, This is an unfavorable situation in which the concentration increases. Under these circumstances, it is the current situation that reformed oil-based xylene is preferably used as a fresh feed material, but in any case, it is necessary to reduce the ethylbenzene concentration, and some methods are industrially used. Was carried out in
Several methods have also been proposed. The methods are roughly classified, one is a method of separating ethylbenzene as it is, and the other is a method of converting it into another useful compound by a reaction.

As a method for separating ethylbenzene, a distillation method can be mentioned. In the case of this method, since the boiling point difference with xylenes is small, it is necessary to use ultra-precision distillation, which requires an enormous industrial investment, and the operating cost is high.
This is an economically disadvantageous method. Furthermore, JP-A-52-102
As shown in Japanese Patent No. 23, etc., there is a proposal to separate ethylbenzene by an adsorption separation method, but the separation performance is not sufficiently satisfactory.

Other methods of removing ethylbenzene include converting it to other useful components. The most typical method is Japanese Patent Publication No. 49-4660.
6,49-47733,51-15044,51-36
253, JP-A-54-16390, a method of converting ethylbenzene into xylene. However, in this method, it is essential that the catalyst contains platinum, which is an extremely expensive noble metal.

Further, in order to convert ethylbenzene into xylene, intervening non-aromatic components such as naphthene and paraffin are required in the reaction mechanism, and the concentration existing in the product is in the range of several% to several tens%. It extends to.
Furthermore, since the conversion rate of ethylbenzene is controlled by thermodynamic equilibrium (Table 2), there are drawbacks such as its limit.

[0012]

[Table 2]

Further, a method of converting ethylbenzene to xylene by a mechanism different from the method using platinum is disclosed in Japanese Patent Publication No. 53-41658. This method uses a catalyst containing ZSM-5, ZSM-12, ZSM-21 zeolite, but this method has a drawback that xylene is slowly isomerized. In particular, in order to isomerize a xylenes having a low p-xylene content, for example, a raffinate fluid obtained by adsorbing and separating p-xylene, it is necessary to highly isomerize m-xylene and also o-xylene to p-xylene. It is a fatal defect to isomerize such xylenes having a low p-xylene content.

A method of changing ethylbenzene to a component other than xylene has been proposed in Japanese Patent Publication No. 53-41657 and Japanese Patent Publication No. 52-148028. This method is to isomerize xylene and at the same time to convert ethylbenzene into benzene and diethylbenzene by a disproportionation reaction, and to separate them using a large boiling point difference with xylene. The benzene thus obtained is in great demand as a raw material for synthetic fiber nylon, but there is almost no demand for diethylbenzene, and it is economically disadvantageous because it needs to be converted into another useful compound.

[0015]

The object of the present invention is to convert an aromatic hydrocarbon by deethylating ethylbenzene to benzene and, at the same time, highly isomerizing xylene and improving the selectivity of the reaction. It is to provide a catalyst and a method.

[0016]

In order to achieve the above object, the present invention is a zeolite in which the size of the main cavity in which less than 50% of all cation sites are exchanged with hydrogen ions is an oxygen 10-membered ring. The present invention provides an isomerization catalyst for xylenes characterized by containing and an isomerization method using the same.

The catalyst of the present invention contains 50% of all cation sites.
The main cavity size, in which fewer sites are exchanged with hydrogen ions, is characterized in that it comprises a zeolite consisting of a 10-membered oxygen ring.

Whether or not less than 50% of all cation sites are exchanged with hydrogen ions can be measured by, for example, an atomic absorption method and fluorescent X-ray. The cations present are previously measured by fluorescent X-rays. The amount A (mol%) of the cation and the amount B (mol%) of sodium in the catalyst are quantified by atomic absorption. Ion-exchange the catalyst many times with an aqueous solution of sodium salt or neutralize it with sodium hydroxide to make a cation site with almost all sodium ions, and wash it thoroughly with distilled water. The amount C of its cation and the amount D (mol%) of sodium ion are determined by atomic absorption. After the catalyst was ion-exchanged many times with an aqueous solution of ammonium chloride, it was calcined to make almost all the cation sites hydrogen ions. Quantify. A, B, C,
The amounts of D, E and F are all values obtained on an absolutely dry basis.
100 x (1- (A + B-E-F) / (C + D-E-
F)) is calculated (this is called the protonation rate), and it can be determined by whether it is less than 50. This can be measured with a catalyst molded product or with zeolite itself.

The silica / alumina ratio of the catalyst of the present invention is preferably less than 35.

The catalyst of the present invention is most effective when used as follows. After contacting xylenes containing ethylbenzene having a paraxylene concentration lower than the equilibrium concentration with the catalyst layer (a) for mainly dealkylating ethylbenzene, less than 50% of all cation sites are exchanged with hydrogen ions. Most preferably, the catalyst is brought into contact with the catalyst layer (b) of the present invention containing a zeolite having a cavity size of 10-membered oxygen ring.

The zeolite used in the catalyst layer (a) may be any one having a dealkylation ability. Zeolite having a main cavity size of 10-membered oxygen ring is preferably used.
Among them, zeolite having a silica / alumina ratio of 35 or more is particularly preferably used.

The size of the main cavity as described above is oxygen 10
Zeolites having a member ring are described in, for example, US Pat.
No. 106 discloses its composition and manufacturing method in Nature.
271,30 March, 437 (1978) whose crystal structure is described in ZSM-5, British Patent 133.
ZSM-8 described in Japanese Patent No. 4243 and ZSM-1 described in Japanese Patent Publication No. 53-23280.
1, ZSM-21 described in U.S. Pat. No. 4,100,346, ZSM-35 described in JP-A-53-144500, zeolite zeta 1 described in JP-A-51-67299, and JP-A-5
The zeolite zeta 3 etc. which are described in 1-67298 gazette.

The zeolite most preferably used in the present invention is synthesized by the method described in JP-B-61-8011. That is, an aqueous reaction mixture containing a silica source, an alumina source, an alkali source, and an aliphatic carboxylic acid or a salt thereof is used in the following composition range: SiO ₂ / Al ₂ O ₃ 5 to 500 5 to ₂₀₀ H ₂ O / SiO ₂ 5 ˜500 10 to 50 OH ⁻ / SiO ₂ 0.01 to 1.0 0.02 to 0.8 A / Al ₂ O ₃ 0.1 to 200 0.5 to 100, the crystal is adjusted. It can be produced by reacting until produced. As the silica source, for example, silica sol, silica gel, silica yellow gel, silica hydrogel, silicic acid, silicic acid ester, sodium silicate or the like is used.

As the alumina source, sodium aluminate,
Aluminum sulfate, aluminum nitrate, alumina sol,
Alumina gel, activated alumina, gamma alumina, alpha alumina, etc. are used. As the alkali source, caustic soda, caustic soda, etc. are used, but caustic soda is preferred. These alkali sources are OH in the system.
^- is preferably added as present in the composition.

The aliphatic carboxylic acid or salt thereof has 1 to 12 carbon atoms, preferably 3 to 6 carbon atoms, specifically, glycolic acid which is a monobasic oxycarboxylic acid,
Lactic acid, hydroacrylic acid, oxybutyric acid or salts thereof, dibasic and polybasic oxycarboxylic acids tartronic acid, malic acid, tartaric acid, citric acid or salts thereof, monobasic carboxylic acids such as formic acid, acetic acid, propionic acid, Butyric acid, valeric acid, acrylic acid, crotonic acid, methacrylic acid or salts thereof, dibasic and polybasic carboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid or their Salt is used. As the salt, a water-soluble salt is preferable.
For convenience, one kind or two or more kinds of these aliphatic carboxylic acids or salts thereof may be used.

The thus-prepared aqueous reaction mixture is crystallized in the form of a slurry as uniform as possible in a closed container such as an iron, stainless steel or Teflon-lined autoclave. The reaction condition for crystallization is a reaction temperature of 80 to 250 ° C., preferably 1
The reaction time is 5 hours to 30 days,
It is preferably 10 hours to 10 days. The reaction mixture is preferably stirred continuously or periodically during crystallization to maintain a uniform state. The crystallized reaction product is taken out from the closed container after cooling, washed with water, filtered, and dried if necessary. Table 3 shows a typical X-ray diffraction pattern of the zeolite thus synthesized.

The X-ray diffraction pattern was measured according to a usual method. That is, for the X-ray irradiation, a diffraction pattern is obtained with a K-α ray of copper using a Geiger equipped with a recording device and a counter spectroscope. From this diffraction pattern, a relative intensity of 10
0I / I ₀ (I ₀ is the strongest line) and the lattice spacing d (unit: nm) are determined.

[0028]

[Table 3] The synthesized zeolite is usually molded by extrusion after mixing with a binder. As the binder, alumina sol, alumina gel, silica sol, titania sol,
Fine particles of inorganic oxides such as zirconia sol and clays such as kaolin, bentonite and montmorillonite are usually used. The amount of binder added is 70% or less, preferably 4
0% or less. In addition to the binder, alumina, silica, zirconia, inorganic oxide powders such as titania also for the purpose of improving moldability, as a good carrier of hydrogenated metal components,
It may be added. In addition to such extrusion molding, compression molding or the like may be used.

The catalyst molded as described above does not have solid acidity as it is. When used in the conversion reaction of aromatic hydrocarbons, it imparts solid acidity to the zeolite,
It needs to be in the acid form. As is well known, the acid type zeolite has, as cations in the zeolite, polyvalent cations having a valence of 2 or more such as hydrogen ion, rare earth ion, alkaline earth metal ion, etc. At least part of the monovalent alkali metal ion is hydrogen ion, ammonium ion,
Alternatively, it can be obtained by performing ion exchange with a polyvalent cation and then firing.

Ion exchange with ammonium can usually be accomplished by contacting the zeolite or shaped body with an aqueous solution of an ammonium salt compound. As the ammonium salt compound, inorganic ammonium salts such as ammonium nitrate, ammonium chloride, ammonium sulfate, ammonium carbonate and aqueous ammonia, or ammonium salts of organic acids such as ammonium formate, ammonium acetate and ammonium citrate can be similarly used, but are more preferable. Is an inorganic ammonium salt. The concentration of the ammonium salt used is preferably a solution of 0.05 to 4 N, but more preferably about 0.1 to 0.5 N. When hydrogen ions are directly introduced, though not particularly limited, it is usually brought into contact with an acid aqueous solution. As a method for ion-exchanging zeolite with an acid and / or ammonium salt solution, either a batch method or a flow method is preferably used. When processing in batch,
The solid-liquid ratio is about 1 or more that zeolite can contact the liquid sufficiently.
L / kg or more is preferable. A treatment time of 0.1 to 72 hours is sufficient, preferably 0.5 to 24 hours. The treatment temperature may be equal to or lower than the boiling point, but it is preferably heated to accelerate the ion exchange rate. When the treatment is carried out by the flow system, a fixed bed system, a fluidized bed system or the like can be used, but it is necessary to take care so that the fluid does not flow unevenly or the ion exchange treatment does not become non-uniform.
The ion-exchanged zeolite is then washed with water. Ion-exchanged water or distilled water is preferably used as the washing liquid, and the washing may be either batch type or flow type.

In this way, hydrogen ions and / or ammonium ions which are hydrogen ion precursors are introduced into the zeolite and calcined to impart solid acidity. In the case of the zeolite used in the catalyst of the present invention, lithium ion is preferably used as such a cation.

The method for obtaining the zeolite in which at least a part of the cation sites other than hydrogen ions are exchanged with lithium ions in this way is not particularly limited, but for example, the above-mentioned hydrogen ions and / or hydrogen ions can be added to a molded zeolite. There may be mentioned a method of performing an ion exchange treatment of introducing a lithium ion at the same time as, or before or after the ion exchange treatment of introducing a precursor ammonium ion. The ion exchange treatment for introducing this lithium ion is generally performed in an aqueous solution. Lithium ions are generally used in inorganic salts such as nitrates, chlorides and sulfates.

After the xylenes containing ethylbenzene having a paraxylene concentration lower than the equilibrium concentration as described above are contacted with the catalyst layer (a) for mainly dealkylating ethylbenzene, less than 50% of all cation sites are present. The size of the main cavity exchanged with hydrogen ions is oxygen 10.
In the case of the isomerization method in which the catalyst layer (b) of the present invention containing a zeolite having a member ring is brought into contact, the zeolite of the catalyst layer (a) also introduces hydrogen ions in the same manner as above. As cations other than hydrogen ions, barium ions and strontium ions are preferably used.

The zeolite of the catalyst layer (a) is preferably treated with a heteropolyacid because the xylene recovery rate is improved. Heteropoly acids are, for example, phosphotungstic acid,
Examples thereof include silicotungstic acid, phosphomolybdic acid, silicomolybdic acid, and the like. These treatments are performed simultaneously with, before, or after the ion exchange treatment. The treatment is usually carried out with an aqueous solution.

The catalyst of the present invention and the catalyst of the catalyst layer (a) preferably contain a hydrogenated metal component. The most preferably used hydrogenated metal component is rhenium. Examples of the method of adding these metals include a kneading method, an impregnation method, and a physical mixing method of powders. Examples of rhenium that can be used include rhenium oxide, perrhenic acid, ammonium perrhenate, and rhenium sulfide. The amount by which rhenium can be expected to be added is 0.005% by weight or more in elemental form, based on the total weight of the catalyst.
However, if the amount of addition is too large, side reactions such as hydrogenolysis reaction will occur at the same time, so it is 3% by weight or less, preferably 1% by weight or less. This optimum value depends on the type of hydrogenated metal component and reaction conditions.

A catalyst obtained by synthesizing zeolite as described above, molding it, subjecting it to ion exchange treatment, and adding a hydrogenated metal is
It is subsequently dried and then calcined. Dry 50 to 2
It is performed at 50 ° C. for 0.1 hour or more, preferably 0.5 to 48 hours. Baking at 300 to 700 ° C. for 0.1 hour or more,
It is preferably carried out at 400 to 600 ° C. for 0.5 to 24 hours. By such calcination, the ammonium ions introduced by the ion exchange treatment are converted into hydrogen ions, and the hydrogen ions are further converted into the decationized type by further increasing the calcination temperature. The resulting catalyst can also be used satisfactorily.

After contacting xylenes containing ethylbenzene having a paraxylene concentration lower than the equilibrium concentration with the catalyst layer (a) for mainly dealkylating ethylbenzene, less than 50% of all cation sites are exchanged with hydrogen ions. In the case of the isomerization method in which the size of the main cavity is a catalyst layer (b) of the present invention containing a zeolite having an oxygen 10-membered ring, the zeolite (A) and the catalyst layer (b) of the catalyst layer (a) are contacted. The abundance ratio of zeolite (B) in the catalyst must be determined by the balance of the activities of both catalysts. For example, when the reaction is carried out using an equal mixture of both zeolites, if the conversion of ethylbenzene is insufficient, the amount of zeolite (A) may be increased relative to that of zeolite B. Since the activities of zeolite (A) and zeolite (B) can be controlled by changing the respective preparation conditions, the optimum mixing ratio of zeolite cannot be unconditionally determined.

The catalyst prepared as described above is used under the following reaction conditions. That is, the reaction operating temperature is 3
The temperature is from 00 to 600 ° C, preferably from 350 to 550 ° C. The reaction operation pressure is from atmospheric pressure to 10 MPa, preferably from atmospheric pressure to 5 MPa. Time factor W / F (g-cat * hr / g-m) that means contact time of reaction
ol feedstock) (W: catalyst weight, F: mole feedstock per hour) is 0.1-200, preferably 1-100. Hydrogen in the reaction system is essential. If the hydrogen concentration is too low, the deethylation reaction of ethylbenzene does not proceed sufficiently, and further, the deposition of the monolayer on the catalyst causes the deterioration of the activity over time. On the contrary, if the hydrogen concentration is too high, the hydrogenolysis reaction will increase, which is not preferable. The hydrogen concentration is 1 to 50 in terms of the molar ratio of hydrogen to the feedstock (hydrogen / F) in the reaction system. This optimum value depends on the type and amount of hydrogenated metal.

A xylene mixture containing ethylbenzene is used as a feed material, but the concentration of ethylbenzene in the xylene mixture is not particularly limited. The para-xylene concentration in the xylene mixture is usually lower than the thermodynamic equilibrium concentration. The feedstock may contain other aromatic components such as benzene, toluene, trimethylbenzene, ethyltoluene, diethylbenzene, ethylxylene and the like. The present invention will be described below with reference to examples.

Example 1 A zeolite having a silica / alumina ratio of 50 was prepared by the method described in JP-A-59-62347 Example 1.
The product obtained was a zeolite having an X-ray diffraction pattern as shown in Table 3.

Example 2 The composition of the reaction mixture was changed to SiO ₂ / Al ₂ O ₃ 25 H 2 O / SiO ₂ 20 OH − / SiO ₂ 0.17 A / Al ₂ O ₃ 2.5 (A is tartaric acid). In addition, zeolite was synthesized in the same manner as in Example 1 except that the addition amount of raw materials was adjusted. The silica / alumina ratio of the produced zeolite was about 20. The obtained zeolite had an X-ray diffraction pattern as shown in Table 3.

Example 3 The zeolite synthesized in Example 1 was mixed with alumina and extruded. Zeolite: Alumina = 2 on an absolutely dry basis
15 as alumina for a mixture with a composition ratio of 5:75
Alumina sol was added and molded so as to contain it by weight. 120
After drying at 50 ° C, and then baking at 500 ° C for 2 hours, 20% by weight of barium nitrate and 44% by weight of ammonium chloride were added to water contained in the molded product, which was twice the weight of the molded product, and zeolite contained in the molded product. It processed at 80 degreeC for 4 hours. After thoroughly washing with warm water of 80 ° C, 0.2% by weight of Re of the molded product was carried, and dried at 120 ° C overnight and then at 520 ° C for 1 hour.
Burned for hours burned. Hereinafter this is referred to as catalyst A.

Example 4 Alumina sol was added to the zeolite synthesized in Example 2 in an amount of 15% by weight as alumina, and extrusion molding was performed. After drying overnight at 120 ° C and then firing at 500 ° C for 2 hours, add 3% by weight of ammonium chloride to the zeolite contained in the molded product and twice the weight of the molded product, and add water at 80 ° C. It was treated for 4 hours. After thoroughly washing with warm water of 80 ° C, 0.2% by weight of Re of the molded product
Was carried out, dried overnight at 120 ° C., and then baked at 520 ° C. Hereinafter this is referred to as catalyst B. The protonation rate of this catalyst was 35%.

A flow reactor was filled with the catalyst A: B = 8: 2. The reaction was carried out under the following reaction conditions.

Reaction temperature 394 ° C., W / F = 30 g · h /
mol, H ₂ /F=3.5 mol / mol, pressure 1MP
a, feed composition: ethylbenzene (EB) 8%, paraxylene (PX) 1%, orthoxylene (OX) 29%,
Meta-xylene (MX) 60%, Toluene (TL) 2% Reaction results are EB conversion 65%, PX / (PX + OX + M
X) = 23.3%, xylene (XY) recovery rate 99.4
%, And non-aromatic components other than ethane were 0.30%.

Comparative Example 1 Alumina sol was added to the zeolite synthesized in Example 2 in an amount of 15% by weight as alumina, and extrusion molding was performed. After drying at 120 ° C overnight and then firing at 500 ° C for 2 hours, add 5% by weight of ammonium chloride to the zeolite contained in the molded product and twice the weight of the molded product to 80 ° C. It was treated for 4 hours. After thoroughly washing with warm water of 80 ° C, 0.2% by weight of Re of the molded product
Was carried out, dried overnight at 120 ° C., and then baked at 520 ° C. for 1 hour. Hereinafter this is referred to as catalyst C. The protonation rate of this catalyst was 55%.

A flow reactor was filled with the catalyst A: C = 8: 2. The reaction was carried out under the following reaction conditions.

Reaction temperature 382 ° C., W / F = 30 g · h /
mol, H ₂ /F=3.5 mol / mol, pressure 1MP
a, feed composition: ethylbenzene (EB) 8%, paraxylene (PX) 1%, orthoxylene (OX) 29%,
Meta-xylene (MX) 60%, Toluene (TL) 2% Reaction results are EB conversion 65%, PX / (PX + OX + M
X) = 23.7%, xylene (XY) recovery rate 98.6
%, And non-aromatic components other than ethane were 0.42%.

Example 5 The zeolite synthesized in Example 1 was mixed with alumina and extruded. Zeolite: Alumina = 2 on an absolutely dry basis
15 as alumina for a mixture with a composition ratio of 5:75
Alumina sol was added and molded so as to contain it by weight. 120
After drying at ℃ overnight, molded product baked at 500 ℃ for 2 hours,
60% by weight of barium nitrate and 10% by weight of ammonium chloride were added to water contained twice as much as the weight of the molded product and zeolite contained in the molded product, and treated at 80 ° C. for 4 hours. 80 ° C
After thoroughly washing with warm water of 0.2%, 0.2% by weight of Re of the molded product is supported and dried at 120 ° C. overnight, then 520
Calcination was carried out at ℃ for 1 hour. Hereinafter this is referred to as catalyst D.

Example 6 Alumina sol was added to the zeolite synthesized in Example 2 so that the alumina content was 15%, and extrusion molding was performed. After drying overnight at 120 ° C. and then firing at 500 ° C. for 2 hours, a 10% lithium nitrate aqueous solution having twice the weight of the molded article was added, and the treatment was repeated 5 times at 80 ° C. for 1 hour.
1% ammonium chloride and 2 times the weight of the molded product were added to the zeolite contained in the molded product, and the mixture was treated at 80 ° C. for 4 hours. After thoroughly washing with warm water of 80 ° C., 0.2% of Re corresponding to the molded product was carried, dried at 120 ° C. overnight, and baked at 520 ° C. Hereinafter this is referred to as catalyst E. The protonation rate of this catalyst was 32%.

Catalyst D: E = 8: 2 was charged into the flow reactor. The reaction was carried out under the following reaction conditions.

Reaction temperature 398 ° C., W / F = 30 g · h /
mol, H ₂ /F=3.5 mol / mol, pressure 1MP
a, feed composition: ethylbenzene (EB) 8%, paraxylene (PX) 1%, orthoxylene (OX) 29%,
Meta-xylene (MX) 60%, Toluene (TL) 2% Reaction results are EB conversion 65%, PX / (PX + OX + M
X) = 23.4%, xylene (XY) recovery rate 99.3
%, And 0.25% of non-aromatic components other than ethane.

Comparative Example 2 Alumina sol was added to the zeolite synthesized in Example 2 in an amount of 15% by weight as alumina, and the mixture was extruded and molded. After drying overnight at 120 ° C, and then firing at 500 ° C for 2 hours, add 10% by weight of ammonium chloride and twice the weight of the molded product to the zeolite contained in the molded product, and add at 80 ° C. It was treated for 4 hours. After thoroughly washing with warm water of 80 ° C, R equivalent to 0.2% by weight based on the molded product
e was carried, dried at 120 ° C. overnight, and then baked at 520 ° C. for 1 hour. Hereinafter this is referred to as catalyst F. The protonation rate of this catalyst was 80%.

Catalyst D: F = 8: 2 was charged into the flow reactor. The reaction was carried out under the following reaction conditions.

Reaction temperature 358 ° C., W / F = 30 g · h /
mol, H ₂ /F=3.5 mol / mol, pressure 1MP
a, feed composition: ethylbenzene (EB) 8%, paraxylene (PX) 1%, orthoxylene (OX) 29%,
Meta-xylene (MX) 60%, Toluene (TL) 2% Reaction results are EB conversion 65%, PX / (PX + OX + M
X) = 23.8%, xylene (XY) recovery rate 95.7%
Met.

Example 7 Alumina sol was added to the zeolite synthesized in Example 2 in an amount of 15% by weight as alumina, and extrusion molding was performed. After drying overnight at 120 ° C and baking at 500 ° C for 2 hours, add 10% lithium nitrate aqueous solution, which is twice the weight of the molded product, and repeat the treatment at 80 ° C for 1 hour 5 times. To the contained zeolite, 3% ammonium chloride and twice the weight of the catalyst water were added and treated at 80 ° C. for 4 hours. After thoroughly washing with warm water of 80 ° C, 0.2% by weight of Re is loaded on the molded product,
After drying at ℃ overnight, it was baked at 520 ℃ for 1 hour. Hereinafter this is referred to as catalyst G. The protonation rate of this catalyst was 45%.

A flow reactor was filled with the catalyst A: G = 8: 2. The reaction was carried out under the following reaction conditions.

Reaction temperature 394 ° C., W / F = 30 g · h /
mol, H ₂ /F=3.5 mol / mol, pressure 1MP
a, feed composition: ethylbenzene (EB) 8%, paraxylene (PX) 1%, orthoxylene (OX) 29%,
Meta-xylene (MX) 60%, Toluene (TL) 2% Reaction results are EB conversion 65%, PX / (PX + OX + M
X) = 23.4%, xylene (XY) recovery rate 99.5%
Met.

Example 8 The zeolite synthesized in Example 1 was mixed with alumina and extruded. Zeolite: Alumina = 2 on an absolutely dry basis
15 as alumina for a mixture with a composition ratio of 5:75
Alumina sol was added and molded so as to contain it by weight. 120
After drying at ℃ overnight, molded product baked at 500 ℃ for 2 hours,
20% by weight of barium nitrate and 10% by weight of phosphotungstic acid are added to twice the weight of the molded product and the zeolite contained in the molded product, treated at 80 ° C for 4 hours, then washed with water, and the molded product weight 40% by weight of ammonium chloride was added to twice the amount of water and zeolite, and the mixture was treated at 80 ° C. for 4 hours. After thoroughly washing with warm water of 80 ° C., 0.2 wt% of Re was loaded on the catalyst, dried at 120 ° C. overnight, and calcined at 520 ° C. Hereinafter this is referred to as catalyst H.

A catalyst of H: E = 8: 2 was charged in a flow reactor. The reaction was carried out under the following reaction conditions.

Reaction temperature 401 ° C., W / F = 30 g · h /
mol, H ₂ /F=3.5 mol / mol, pressure 1MP
a, feed composition: ethylbenzene (EB) 8%, paraxylene (PX) 1%, orthoxylene (OX) 29%,
Meta-xylene (MX) 60%, Toluene (TL) 2% Reaction results are EB conversion 65%, PX / (PX + OX + M
X) = 23.4%, xylene (XY) recovery rate 99.6%
Met.

Example 9 The zeolite synthesized in Example 1 was mixed with alumina and extruded. Zeolite: Alumina = 2 on an absolutely dry basis
15 as alumina for a mixture with a composition ratio of 5:75
Alumina sol was added and molded so as to contain it by weight. 120
After drying at ℃ overnight, molded product baked at 500 ℃ for 2 hours,
20% by weight of strontium nitrate and 40% by weight of ammonium chloride were added to twice the weight of the molded product and the zeolite contained in the molded product, and the mixture was treated at 80 ° C. for 4 hours.
After thoroughly washing with warm water of 80 ° C.
2% by weight of Re was carried, and after drying at 120 ° C. overnight,
It was baked at 520 ° C. for 1 hour. Hereinafter this is referred to as catalyst I.

Catalyst I: E = 8: 2 was charged into the flow reactor. The reaction was carried out under the following reaction conditions.

Reaction temperature 394 ° C., W / F = 30 g · h /
mol, H ₂ /F=3.5 mol / mol, pressure 1MP
a, feed composition: ethylbenzene (EB) 8%, paraxylene (PX) 1%, orthoxylene (OX) 29%,
Meta-xylene (MX) 60%, Toluene (TL) 2% Reaction results are EB conversion 65%, PX / (PX + OX + M
X) = 23.4%, xylene (XY) recovery rate 99.4%
Met.

[0065]

When xylene containing ethylbenzene is isomerized using the catalyst of the present invention, dealkylation of ethylbenzene and isomerization of ortho-xylene and meta-xylene to para-xylene can be achieved in a well-balanced manner. The hydrogenolysis of the ring is also suppressed, and the xylene recovery rate is improved.

Claims (14)

[Claims] 1. A catalyst for isomerization of xylenes, characterized in that less than 50% of all cation sites are exchanged with hydrogen ions, and that the zeolite contains a zeolite having a main cavity size of a 10-membered oxygen ring. . 2. A zeolite in which the size of the main cavity is a 10-membered ring of oxygen is 1.12 ± 1 in terms of lattice spacing d (nm).
0.02, 1.01 ± 0.02, 0.386 ± 0.00
8, 0.372 ± 0.008 and 0.365 ± 0.00
The isomerization catalyst for xylenes according to claim 1, which exhibits an X-ray diffraction pattern having a peak at position 8. 3. The xylene isomerization catalyst according to claim 1, which contains a rhenium component. 4. The xylene isomerization catalyst according to claim 1 or 2, wherein the silica / alumina ratio of the zeolite is less than 35. 5. The xylene isomerization catalyst according to claim 1, wherein at least a part of cation sites other than hydrogen ions is exchanged with lithium. 6. A catalyst comprising a zeolite containing less than 50% of all cation sites exchanged with hydrogen ions and having a main cavity size of a 10-membered oxygen ring, and ethylbenzene having a paraxylene concentration lower than the equilibrium concentration. A method for isomerizing xylenes, which comprises contacting xylenes containing. 7. A zeolite in which the size of the main cavity is a 10-membered oxygen ring is 1.12 ± 1 in terms of lattice spacing d (nm).
0.02, 1.01 ± 0.02, 0.386 ± 0.00
8, 0.372 ± 0.008 and 0.365 ± 0.00
The method for isomerizing xylenes according to claim 6, which shows an X-ray diffraction pattern having a peak at position 8. 8. The method for isomerizing xylenes according to claim 6, wherein the catalyst contains a rhenium component. 9. The method for isomerizing xylenes according to claim 6, wherein the silica / alumina ratio of the zeolite is smaller than 35. 10. The method for isomerizing xylenes according to claim 6, wherein at least a part of cation sites other than hydrogen ions is exchanged with lithium. 11. After contacting xylenes containing ethylbenzene having a paraxylene concentration lower than the equilibrium concentration with a catalyst layer (a) for mainly dealkylating ethylbenzene, less than 50% of all cation sites are hydrogen ions. 7. The method for isomerizing xylenes according to claim 6, wherein the catalyst is contacted with a catalyst layer (b) containing a zeolite which is exchanged and has a main cavity size of an oxygen 10-membered ring. 12. A catalyst layer (a) comprising a zeolite having a 10-membered oxygen ring as a main cavity in which at least a part of cation sites are exchanged with hydrogen ions and barium ions and / or strontium ions. The method for isomerizing xylenes according to claim 11, wherein 13. A zeolite having a 10-membered oxygen ring whose main cavity size is 1.12 ± 0.
02, 1.01 ± 0, 02, 0.386 ± 0.008,
13. The method for isomerizing xylenes according to claim 11 or 12, which shows an X-ray diffraction pattern having peaks at positions of 0.372 ± 0.008 and 0.365 ± 0.008. 14. The method for isomerizing xylenes according to claim 11, 12 or 13, wherein the catalyst layer contains a rhenium component.